Gas turbine engines may include a low pressure compressor and a high pressure compressor. In many engine configurations, a low pressure compressor case surrounds the low pressure compressor and a high pressure compressor case surrounds the high pressure compressor with a compressor intermediate case located therebetween. The area located between the low pressure compressor case and the high pressure compressor case is commonly referred to as station 2.5. Station 2.5 generally includes a 2.5 bleed path through the compressor intermediate case to allow air to bleed into the fan stream. In addition to relieving pressure when the engine is at idle or low power, the 2.5 bleed path also allows dirt particles from the low pressure compressor discharge air to exit into the fan stream, so that cleaner air passes downstream through the core engine. The 2.5 bleed path is traditionally regulated by a 2.5 bleed valve that controls the amount of bleed air flowing to the fan stream. In many configurations, the 2.5 bleed valve is located in the core compartment to facilitate maintenance.
An environmental control system bleed path may also be implemented in gas turbine engines. The environmental control system bleed path guides the air to the environmental control system for supplying air to the cabin of an aircraft. Conventional environmental control system bleed paths are usually sourced from the middle section of the high pressure compressor. While effective, the environmental control system air sourced from the middle section of the high pressure compressor may contain dirt particles that were not diverted through the 2.5 bleed path. However, cleaner environmental control system bleed air is desirable because this air eventually circulates throughout the aircraft cabin and is breathed in by the passengers.
Accordingly, there is a need to provide cleaner environmental control system bleed air into the aircraft cabin such as by sourcing this air from station 2.5 immediately downstream of the 2.5 bleed path so that there is minimal disruption to the core air flow.